/*
 * Copyright (c) 2009, Hamish Morgan. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the University of Sussex nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package locusts.lib;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

/**
 *
 * @author Hamish Morgan
 */
public class ObjectIdFactory {

    private static final int FIRST_ID = 0;
    private Map<Class<? extends Object>, AtomicInteger> nextIds;

    private ObjectIdFactory() {
        nextIds = new ConcurrentHashMap<Class<? extends Object>, AtomicInteger>();
    }

    private static class InstanceHolder {

        private InstanceHolder() {
        }
        private static ObjectIdFactory INSTANCE = new ObjectIdFactory();
    }

    public static ObjectIdFactory getInstance() {
        return InstanceHolder.INSTANCE;

    }

    public static final 
//            synchronized
            int nextIdFor(
            Class<? extends Object> c) {
        ObjectIdFactory instance = ObjectIdFactory.getInstance();

        if (!instance.nextIds.containsKey(c)) 
            instance.nextIds.put(c, new AtomicInteger(FIRST_ID));

        return instance.nextIds.get(c).getAndIncrement();
//
//        final int nextId = instance.nextIds.get(c);
//        if (nextId == Integer.MAX_VALUE) {
//            throw new RuntimeException();
//        }
//        instance.nextIds.put(c, nextId + 1);
//        return nextId;
    }

    public static final 
//            synchronized
            void setNextId(Class<? extends Object> c,
            int id) {
        ObjectIdFactory instance = ObjectIdFactory.getInstance();
        if (!instance.nextIds.containsKey(c)) 
            instance.nextIds.put(c, new AtomicInteger(FIRST_ID));
        instance.nextIds.get(c).set(id);
//        instance.nextIds.put(c, id);
    }
}